Most skin cancer is the result of exposure to ultraviolet radiation from the sun, which suppresses the skin’s immune system making people less able to fight off skin diseases such as cancer. But researchers in England have shown that a daily dose of omega-3 can partially counteract this effect, reducing an individual’s likelihood of developing skin cancer. The fatty acids have been shown to prevent cancer in mice, but this was the first time it was demonstrated in humans.

Some of the most exciting medical research these days involves light. Light therapy for cancer, in which a tumor-seeking dye becomes toxic as soon as a light is switched on, manages to avoid slaughtering nearby healthy cells. Optogenetics—using light to turn on or off the expression of neurons—has advanced researchers’ understanding of neurological diseases.

Now, a recent paper is a reminder that light might someday be used for exquisitely tailored drug delivery: in this paper, tiny packages bearing all the molecular machinery to build a protein are idle when injected into mice, but spring into action when exposed to UV light.

What’s the News: Researchers have pinpointed the molecule that makes sunburned skin so sensitive to pain, they reported yesterday in Science Translational Medicine. This finding could help scientists develop new painkillers not only for sunburn, but for chronically painful conditions such as arthritis.

Yale researchers have found that male butterflies do not always take the lead in courting females at mating times. In some instances it’s the females that open the negotiations, and, curiously, the deciding factor seems to be the conditions in which they grew up as larvae—whether it was the dry, cool season, or the wet and warm season.

When certain caterpillars are raised in warm, moist conditions they grow into what some would consider traditional roles — males pursuing demure females. But new research has found that when they are raised in dry, cool conditions, it’s the ladies that become aggressive adults, actively courting the guys. [AP]

Among squinting bush brown butterflies, the species tracked in this study, both male and female sport what look like eye spots on their wings. The white spots in the center (the pupil of the eye) reflect light in the ultraviolet range, which appears to be the key to the butterflies‘ mating behavior.

“Cool temperatures increase the UV reflectance of female sexual ornaments, warmer temperatures increase the UV reflectance of male sexual ornaments. These changes are not visible to humans because we do not see UV,” explains postdoctoral fellow Dr Kathleen Prudic. However butterflies can see UV, so by developing more attention-grabbing eye spots, females born in the dry season are able to attract males. [BBC News]

Whales don’t wear sunscreen. And because these massive sea mammals must surface to breathe, they are being exposed to more and more ultraviolet radiation sneaking through the weakened ozone layer. According to Karina Acevedo-Whitehouse, lead author of a study in the Proceedings of the Royal Society B, some whales are getting serious sunburns at an alarming rate.

From 2007 to 2009, her team sampled fin, sperm, and blue whales in the sun-drenched Gulf of California, which is the long, skinny expanse of water between mainland Mexico and Baja California.

Nearly all of the skin samples contained “sunburn cells,” abnormal cells associated with ultraviolet-induced DNA damage. These indicators were even found in the lowest layer of skin on the whales, suggesting that those individuals were suffering from very severe sunburns. [Discovery News]

We know that there’s a whole spectrum of different wavelengths of light beyond the puny band of visible light we humans can see. And we knew that some animals, like certain species of fish and birds, have vision that extended beyond ours into wavelengths like ultraviolet. But a new study in Current Biology demonstrates that not only can damselfish see in UV, but that they can discern specific patterns in UV light, which is much more than we ever gave them credit for.

The findings are the first to show an animal “that is able to discriminate between fine-scale UV patterns using only their short-wavelength receptors (UV cones),” the researchers wrote in their study. These fish seem to use the UV cues to distinguish their own from other similar-looking species [Scientific American]. Prior to this, many researchers thought the fish’s UV vision just allowed them to detect the presence of UV light, and wasn’t refined enough to detect any kind of patterns.

Feel like teaching a lesson to that pinhead-sized worm that’s been bothering you? According to a study in the Journal of the American Chemical Society, a material called dithienylethene plus a blast of UV light can stop a worm in the midst of its worming, rendering it temporarily paralyzed.

The researchers fed a light-sensitive material — a “photoswitch” known as dithienylethene — to the transparent worms. When exposed to ultraviolet rays, the molecule turned blue and the worms became paralyzed. Using visible light instead made the chemical turn colorless and the paralysis ended [LiveScience]. Scientists aren’t sure why the transparent nematodes became paralyzed, but they know dithienylethene changes shapes and suspect it interferes with the worm’s energy-producing metabolic pathways. Repeated cycles of UV-induced paralysis actually killed some of the worms.

Unsurprisingly, news of this worm stun-gun led to longing for Star Trek-style phasers, and the scientists, though skeptical, were good sports about it. As lead researcher Neil Branda said tactfully: “I’m not convinced there’s a legitimate use of turning organisms on and off in terms of paralysis, but until somebody tells me otherwise, I’m not going to say that there isn’t an application” [BBC News].

But while phasers remain a fantasy, light-activated materials certainly have a future in medical research. Light-activated drugs could be used to activate tumour-killing drugs once they reach a particular location in the body. Similar chemicals have been used before, but have required a steady supply of light – often harmful UV bandwidths – to stay active. The new compounds, known as diarylethenes, could be more useful because they can be switched on and off with a single light pulse, Branda says [New Scientist].